In recent years fiber optic light transmission systems, wherein a single optically conductive fiber or multiplicity of parallel optically-conductive fibers are arranged to form a flexible light-conductive cable bundle for conveying light from one location to another, have come into increasing use, not only for providing illumination, but also for conveying data from one location to another. In the latter application, a light source is modulated with data to be transmitted at one end of the cable bundle, and the data is recovered at the other end of the cable bundle by a photo-sensitive detector. Since the data is conveyed by a medium not subject to radio frequency interference or detection, such light transmission systems are particularly well adapted for high security applications, such as found in the data processing and military communications field.
With the increasing use of fiber optic systems, the need has developed for a connector for optically coupling segments of light-conductive cables with minimum detriment to the optical transmission path. It is generally well known that to achieve efficient light transfer between a pair of fiber optic cables, the optical fibers of the cables must be axially and angularly aligned and as close together as possible without touching. Where the fiber optic cables are used for conveying data, as the data transmission frequency is increased, the diameters of the fiber optic cables must decrease to avoid dispersion and other deleterious effects within the optical transmission path. Data transmission frequencies have increased to the point where only a single optical fiber is utilized for conveying the data. As a result, the absolute magnitude alignment tolerance of the optical fiber ends is extremely small.
It has been found that extremely strict axial and angular alignment between a pair of fiber optic cables can be achieved by terminating the optical fibers of the cables in connector terminating pin assemblies with the optical fibers disposed along a preselected axis within the pins. As a result, when a pair of terminating pins having optical fibers therein disposed along a preselected axis are aligned, the optical fiber terminating ends will also be in close alignment. It has been found that accurate alignment of optical fiber ends may be best achieved when the optical fibers are terminated within the terminal ends of the terminating pins concentrically aligned with respect to the outer dimensions of the terminating pin terminal ends. As a result, when a pair of such terminating pins are concentrically and accurately aligned, the optical fibers will likewise be accurately aligned for efficient light transfer with such alignment also being independent of pin rotation.
Many techniques have been devised for aligning optical fibers concentrically with respect to the outer dimensions of connector terminating pin assemblies. One such technique which has proven successful is fully disclosed and claimed in copending application Ser. No. 806,953, filed June 15, 1977 in the name of the inventor of the present invention, and which is assigned to the assignee of the present invention. The connector disclosed in that application includes a cylindrical terminating pin having a longitudinal bore extending into the rear end of the terminating pin and a counterbore extending into the terminating pin from the terminal end of the pin. The counterbore has inner walls which are concentric with respect to the outer dimension of the cylindrical terminating pin and communicates with the longitudinal bore. A plurality of pin members of equal diameter are within the counterbore and arranged in side-by-side relation for substantial tangential contact with the inner walls of the counterbore and substantial tangential contact with each other. As a result, an optical fiber threaded through the longitudinal bore, the counterbore, and the central passageway defined by the pin members is concentrically aligned within the central passageway defined by the pin members with respect to the outer dimension of the terminating pin.
While the foregoing technique has been found to be commercially successful and provides alignment of the optical fibers for efficient light transfer, the practice of the technique is tedious. Trained personnel are required for placing the pin members within the counterbore because the pin members are extremely small and knowledge of the intended result is necessary. Also, because a plurality of component parts are involved, successful practice of the technique is time-consuming and does not lend itself to mass production techniques.
It is therefore a general object of the present invention to provide a new and improved apparatus for aligning an optical fiber within the terminal end of a connector terminating pin assembly concentrically with respect to the outer dimension of the terminating pin.
It is another object of the present invention to provide an apparatus for aligning an optical fiber within a terminating pin which lends itself to mass production techniques.
It is a still further object of the present invention to provide a new and improved apparatus for terminating an optical fiber within a terminating pin which requires a minimum number of component parts to be utilized and which may be performed by unskilled personnel.